Sphere packing is a mathematical concept that involves arranging spheres in a way that maximizes the amount of space they occupy. This can be visualized by stacking oranges in a grocery store or arranging balls in a box. The goal is to find the most efficient way to fill a given volume with spheres, minimizing the empty space between them. One of the most famous arrangements is the face-centered cubic packing, which achieves about 74% efficiency. This means that in a given volume, 74% can be filled with spheres, while the remaining 26% is empty space. Sphere packing has applications in various fields, including crystallography and materials science.